Blood perfusion changes during sacral nerve root stimulation versus surface gluteus electrical stimulation on in seated spinal cord injury

Objective: To examine dynamic changes of ischial blood perfusion during sacral nerve root stimulation against surface functional electrical stimulation (FES). Methods: Fourteen adults with suprasacral complete spinal cord injury were recruited. The gluteal maximus was activated by surface FES or stimulating sacral nerve roots by functional magnetic stimulation (FMS) or a sacral anterior root stimulator implant (SARS). Ischial skin index of haemoglobin (IHB) and oxygenation (IOX) was measured. Results: Skin blood perfusion was significantly higher during FMS than the baseline (IHB 1.05±0.21 before vs. 1.08±0.02 during stimulation, P=0.03; IOX 0.18 ± 0.21 before vs. 0.46 ± 0.30, P=0.01 during stimulation, n=6). Similarly, when using the SARS implant, we also observed that blood perfusion significantly increased (IHB 1.01 ± 0.02 before vs. 1.07 ±0.02 during stimulation, P=0.003; IOX 0.79±0.81 before vs. 2.2±1.21 during stimulation, P=0.03, n=6). However, there was no significant change of blood perfusion during surface FES. Among 4 participants who completed both the FMS and FES studies, the magnitude of increase in both parameters was significantly higher during FMS. Conclusion: This study demonstrates that using SARS implant is more efficient to activate gluteal muscles and confer better benefit on blood perfusion than applying traditional FES in SCI population